Resurfacing valve seat



Aug- 25, 1935- Y H. G. MILLER 2,052,101

REsURFAciNG VALVE SEAT Filed Fb. 5, 1934 I 2 Sheets-Sheet l Allg-V 25, 1936. H. G. MILLER I I Y RESURFACING VALVE SEAT Filed Feb. 5, 1934 2 Sheets-Sheet 2- sov Patented Aug. 25, 1936 UNITED STATES PATENT orties 3 Claims.

My invention relates toV resurfacing valve seats.

One of the objects of my invention is to provide an improved method of resurfacing Valve seats in which the resurfacing tool will be accurately centered.

A further object of my invention is to provide improved method of resurfacing valve seats of the type in which the valve moves outwardlyin its seating movement, such as certain types of airplane motors.

A further object is to provide an improved method of resurfacing the, valve seats comprising the use of a tubular pilot through which part of the transmission for the resurfacing cutter extends.

A further object of my invention is to provide an improved method of resurfacing a valve seat which will make the seating surface gas-tight, thereby preventing the blow torch action of the hot gases which causes an abnormal rise in the temperature of the motor head, causes excessive gas and oil consumption, and impairs the efciency of the motor performance.

Further. objects will be apparent from theA specification and claims.

subject matter of my copending applications Serial No. 625,277, filed July 28, 1932, and Serial No. 630,334, led August 25, 1932. l

In the drawings, in Ywhich an embodiment of my invention is shown,

Figure 1 is an axial sectional view showing the valve seat, valve stem guide and associated parts of a known type of airplane motor;

Fig. 2 is an axial sectional view showing the parts of Fig. 1 and, in addition, showing the use of a tool for cleaning and scraping the valve stem guide and coaxially counterboring the ends of the valve stem guide; j

` Fig. 3 is an axial sectional view showing a further step in my method including the installation of the cutter pilot and feed mechanism;

Fig. 4 is an axial sectional View showing a fur. ther stepV of my method including the putting in place of the roughing cutter on the pilot and the connection therewith of the operating mechanism for the roughing cutter;

Fig. 5 is an axial sectional view showing a further step including the use of the finishing cutter after the roughing cutter has done its work;

Fig. 6 is a transverse section on the line 6-6 of Fig. 5; 1

Fig. 'l is a transverse section on the line 1 1 of Fig. 5;

Fig. 8 is a transverse section on the line 8--8,

(Cl. .Z9-156.7)

of Fig. 2, showing the cleaning and scraping shank; and

Fig. 9 is an enlarged sectional view showing the counterbored valve stem guide and pilot.

Referring to the drawings in detail, and following the successive steps, 'the constructionV shown in Fig. 1 comprises a valve seat l and valve sternY guide 2 of va known type of airplane motor, for use with a valve which seats by an outward movement. In use, the constant reciprocating movement of the valve stem in the guide causes this guide tobecome worn, particularly at the ends, forming a sortV of bell mouth at each end of the valve stem guide. This wearing of the valve stem guide results in imperfect seating of the valve, permitting the leakage of gas with the consequent undesirable effects as pointed out above of increasing the motor head temperature, burning the valve seat, and excessive oil and gas consumption.

g Heretofore it has been common, when it became necessary to resurface the valve seat, to fit the pilot into the worn valve stem guide to' provide a centering means for the resurfacing cutter. Due to the irregular worn condition of the valve stem guide, the pilot would t loosely` and not be accurately centered with respect to the seat so that the seat itself would not be ground coaxially with the unworn portion of the valve stemguide and would not be resurfaced in a plane at right angles to the axis of the unworn portion ofthe valve stem guide.

I [n order to provide for accurate centering of the pilot, I provide a tool for cleaning and scrapingthe internal surface of the valve stem guide throughout its length and for counterboring both ends of the valve stem guide to provide an accurate centering for the pilot which in turn centers the resurfacingcutter.

This scraping and counterboring tool, shown in Fig. 2, comprises Va cleaning and scraping shank 3 which extends throughout practically the entire extent of the valve stem guide, a counterboring portion 4 for effecting a counterbore at the outer end of the valve stem guide, and a counterboring portion 5 for effecting a counterbore at the inner end ofV the valve stem guide. The cleaning and scraping portion v3' has the general appearance of a reamer but the contour of the scraping blades 6 of the reamer is circular in transverse section, as shown in Fig. 8, so thatno clearance is provided foi-,these scraping blades and consequently there will be little or no cuttingraction on the internal surface of the valve stem guide but only a clean,- inguand scraping action'suicient to clean and scrape the internal surface of the valve stem guide thoroughly.

A tool is chosen having a shank which will fit snugly in the valve stem guide so that the rotation of this scraping shank will effectively clean the inner surface of the valve stern guide. Also, due to the snug t of this scraping shank of the valve stern guide, it will serve to center accurately the tool with respect to the valve stem guide to cause the counterbores at the ends of the guide to be perfectly coaxial with respect tothe unworn portion of the valve stern guide. The two counterboring portions are similar in nature, being in general of an end milling cutter type suitable for providing a cylindrical counterbore in each end of the valve stem guide. In order to adjustably limit the depths of the counterbore, stop collars 'I are provided which may be set at the desired points on the shank of the tool by means of set screws 8. These collars limit the depth of the counterbore by coming in contact with the ends of the valve stem guide.

A suitable operating handle 9 is provided having a bayonet joint connection II) with the shank of the tool. The outer counterbore is effected by pressing inwardly on the operating handle as it is rotated and the inner counterbore is effected by pulling out on the operating handle as it is rotated.

Fig. 3 shows a further step in the method in which the counterboring and scraping tool is removed and the pilot and feed mechanism for the cutter is put in place. This pilot and feed apparatus comprises a pilot II having a tubular portion extending completely through the valve stem guide, an enlarged cylindrical arbor portion I 2 having a force fit in the inner counterbore, a clamping sleeve I3 having threaded engagement with the outer end of the tubular pilot and having an annular shoulder portion, the end of which has a force fit with the outer counterbore, and a feed nut I4 having threaded engagement with the outer end of the clamping screw I3. Axial openings are provided through the feed screw I4 and clamping sleeve I3 in alignment with the opening through the tubular pilot to provide for the insertion of an operating shaft for the cutter hereinafter referred to.

In putting the pilot and feed mechanism in place, the tubular pilot II is separated from the clamping sleeve I3 and inserted into the valve stern guide 2 from the-inside of the cylinder (see Fig. 5). The clamping sleeve I3 is then threaded onto the end of the tubular pilot and screwed up tight to bring the parts I 2 and I3 into snug forced engagement with the counterbores in the valve stem guide respectively. This centers the pilot I I with precision, insuring that the cutter will be coaxial with the unworn portion of the valve stern guide.

Fig. 4 shows the next step which is the putting in place of the roughing cutter and the operating mechanism therefor. This roughing cutter mechanism comprises a cutter head I4 mounted for rotational and axial movement on the tubular arbor I2 of Fig. 3, an operating handle I5 for rotating a shaft I6 which extends through the tubular pilot and associated parts and gear reduction mechanism between this shaft I6 and the cutter head I4 to lessen the torsional strain on the shaft and provide increased torque for the cutter head. This gear reduction mechanism between the shaft and the cutter head (see Fig. 7) comprises a drive pinion II rotatable with the shaft I6, a plurality of pinions I8- surrounding and meshing with this central drive pinion, a supporting plate or spider I9 on which these pinions are mounted, held against rotation by means of a hexagonal sleeve 2l) on which the plate I9 is mounted fitting in a hexagonal opening in the tubular pilot and a ring gear 2l meshing with the pinions I8 and secured to the cutter head I4 whereby the cutter head is rotated at a reduced speed as compared with the shaft I 6 and in the opposite direction. In practice, I have found that a gear reduction of about 3 to 1 gives satisfactory results.

The cutter head I4 comprises a sleeve portion 22 having a nice running t on the pilot, whereby the cutter head is accurately centered with respect to the pilot, which, in turn, is accurately centered with respect to the valve stem guide. This cutter head sleeve 22 may be secured to the ring gear 2| by means of a bayonet joint connection 23, a set screw 24 being provided to prevent disconnection of this bayonet joint. The ring gear 2l may be secured to a bearing cap 25 by means of suitable screws 26. A suitable antifriction bearing may be provided between the bearing cap 25 and the extended hub 21 of the pinion I'I.

The inner raceway 28 of the anti-friction bear-V ing may be clamped in place between the planet pinion retaining plate 2S and a bearing lock nut 30 threaded 4onto the extended hub 2l of the center pinion Il. The operating shaft I6 has a bayonet joint connection 3l with this extended hub 2'I so that the cutter head and gear reduction assembly may be slipped into place from the inside of the cylinder, and the operating shaft I6 may be slipped into place from the outside of the cylinder and readily engaged with the extend-,. ed hub of the pinion by reason of the aforesaid bayonet joint connection 3I. The bayonet joint connection is so designed that the rotational operating movement of the shaft will hold it in connected position. The shaft may be readily disconnected from the cutter head simply by rotating it backward far enough to enable the bayonet joint to be disconnected.

For feeding the cutter head toward the valve seat, the feed nut I4 is turned by hand in a direction to press it against the anti-friction bearing 32 provided between the feed nut and the hub 33 of the operating handle I5. It is customary to grind two different zones of the valve seat at different angles. This is accomplished by pairs of cutters 34, 35 having different degrees of angularity with respect to the axis of the valveseat.: This provides a relatively narrow zone on which the finishing cutter hereinafter referred to operates in order to provide a smooth narrow zone on which the conical valve may seat perfectly.

The next step is the finishing operation shownin Fig. 5 which involves simply the substitution of a finishing cutter head 36 for the roughing cutter head shown in Fig. 4. This finishing cutter 36.

may be of the type shown in my copending application, Serial No. 56,490, filed Dec. 28, 1935, having irregularly spaced cutting teeth of different slopes, some having positive rake and others negative rake, and some of the cutting edges being right-hand spirals and others being left-hand spirals. The nishing cutter head is accurately centered on the tubular pilot which in turn is accurately centered kin the valve stem guide so that the valve seat will be finished accurately and coaxially with respect to the valve stem and in a plane at right angles with respect thereto. The

finishing cutter 36 may have a bayonet joint con- 75 nection with the ring gear 2l and be held in place by the set screw 24.

In Fig. the apparatus is shown installed in position for resurfacing one of the valve seats of a known type of airplane motor cylinder mounted in a special vise for holding the work in convenient position for operation. This vise comprises a base 31 which may be adjustably mounted to swivel about a clamping bolt 38 and an annular supporting flange 39 carried by the base against which the annular ange 40 of the cylinder is clamped by means of hook-shaped clamping bolts 4I. By means of the two swivel adjustments, the cylinder can be mounted in any desired position which will be most convenient for the operation of the reseating apparatus. If desired, a swivel bracket 42 for a lamp socket may be provided so that the lamp can be swung from a position in which it will illuminate the interior of the cylinder to a position out of the way of the cylinder in which easy access may be ha-d for the insertion of the pilot and cutter head.

The use of the apparatus has been outlined in connection with the description of the Various apparatuses successively employed. To recapitulate the rst step is the cleaning and scraping of the valve stem guide 2 and the counterboring of the ends of the guide, as shown in Fig. 2. These counterbores are coaxial with respect to the valve stem guide because of the centering effect of the scraping and cleaning shank 3.

The next step is the insertion -of the pi1ot and feed mechanism shown in Fig. 3, the pi1ot Il being accurately centered by means of the counterbores previously formed. The next step is the putting in place of the roughing cutter head and the operating mechanism therefor shown in Fig. 4, and the operation of this roughing cutter mechanism to nish the valve seat roughly by providing two conical zones of different slopes.

The next step is the putting in place and operation of the finishing cutter head shown in Fig. 5. It will be seen that the above-described use of this apparatus results in a smoothly nished valve seat ground coaxially with respect to the valve stem guide and in a general plane at right angles with respect to the valve stem guide, thus providing a leakless valve seat and preventing the undesirable eifects of excessive temperature in the motor head, excessive wear of the valve and valve seat because of the blow torch action of the hot gases, and excessive oil and gas consumption.

Further modifications will be apparent to those skilled in the art and it is desired, therefore, that my invention be limited only by the prior art and the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A method of surfacing a valve seat which is provided with an elongated cylindrical valve stem guideway, comprising forming a counterbore adjacent one end of said guideway and coaxial therewith, and using said coaxial counterbore as a centering means for valve seat surfacing apparatus.

2. A method of surfacing a valve seat which is provided with an elongated cylindrical valve stem guideway, comprising forming two counterbores, one adjacent each end of sai-d guideway and coaxial therewith, and using said counterbores as a centering means for valve seat surfacing apparatus.

3.v A method of surfacing a valve seat which is provided with an elongated cylindrical valve stem guideway, comprising forming a counterbore adjacent one end of said guideway and coaxial therewith, and using said coaxial counterbore and elongated guideway as centering means for valve seat surfacing apparatus.

.. HARRY G. MILLER. 

